The puffy curly hair, usually very untidy, on the back of a hairy dude's neck. Commonly associated with overweight to obese men. Typically used as an all-purpose pillow or 100% effective contraception.

Becky: So what did you think of Ricky?
Katelyn: He's a nice guy, but he has a huge neck fro!
Becky: Ewww, good thing he doesn't have your number.